1. Field of the Invention
This invention relates to an outboard motor steering control system.
2. Description of the Related Art
In recent years, outboard motor steering control systems have been developed that eliminate the need for mechanical connection between the steering wheel and the steering mechanism of the outboard motor, as taught, for example, by Japanese Laid-Open Patent Application No. 2002-187597, particularly paragraphs 0022, 0025 and 0027 and FIG. 1. The outboard motor steering system taught by the reference is equipped with an actuator for steering the outboard motor and a rotation angle sensor for detecting the rotation angle of the steering wheel. The system controls the steering angle of the outboard motor by regulating the drive current to be supplied to the actuator based on the detected rotation angle.
Higher accurate control of the outboard motor steering angle to a desired value (i.e., a desired steering angle matched to the detected rotation angle of the steering wheel) can be achieved, for example, by additional implementation of feedback control on the technique set out in the reference. One specific way of achieving such control is to provide a steering angle sensor for detecting the steering angle of the outboard motor in addition to the rotation angle sensor for detecting the rotation angle of the steering wheel and control operation of the actuator so as to eliminate the error between the detected and desired steering angle values. However, this has a problem in that steering becomes impossible when the steering angle sensor fails.